There is a known image formation apparatus for forming a color image by transferring ink of respective colors by sublimation or melting from an ink ribbon on which a set of ink layers in a plurality of colors are repeatedly applied in a ribbon direction, to an identical transfer region on an image formation target object by using a thermal head.
In Japanese Patent No. 4,337,582, a printing apparatus of a re-transfer scheme that contains this image formation apparatus is described. The ink ribbon to be used in this printing apparatus has four colors of yellow (Y), magenta (M), cyan (C), and black (BK), and the image formation target object is a ribbon shaped intermediate transfer film.
In the printing apparatus as disclosed in Japanese Patent No. 4,337,582, the color image is formed by transferring the ink of respective colors to an identical transfer region (hereafter the transfer region is also referred to as a frame) in the intermediate transfer film one color by one color, as the thermal head is put in pressed contact with a face on opposite side of the ink layer, while moving the ink ribbon in a ribbon direction with its ink layer overlapping with the intermediate transfer film.
Namely, for each color, operations of separating the thermal head, winding and cueing one frame part of the intermediate transfer film, and putting the thermal head into pressed contact are carried out in this order.
Consequently, in order to form the color image using the ink of four colors, a cueing operation is carried out four times (a winding operation is carried out three times), for the intermediate transfer film.
In Japanese Patent No. 4,337,582, in each set of the ink layers on the ink ribbon, a cueing mark 11c for the purpose of a cueing operation for each set is given in advance to a leading position of the ink layer of the yellow (Y) that is the first transfer color. Also, a frame mark 21d for the purpose of a cueing operation for a frame is given in advance to a leading position of each frame in the intermediate transfer film.
The printing apparatus as disclosed in Japanese Patent No. 4,337,582 has a re-transfer apparatus (or a re-transfer unit) for carrying out a re-transfer operation in which the color image that has been formed on the intermediate transfer film is transferred again to a re-transfer target object such as a card.
Now, to a face on opposite side (hereafter also referred to as a back face) of a face on a side applied with the ink layer (hereafter also referred to as an ink face) in the ink ribbon, in order to make a sliding movement of the thermal head smooth, a lubricant is applied as a back coat agent.
The lubricant has a lubricating property with a different temperature characteristic for each type.
For example, among the general purpose lubricants of relatively low cost, there are those for which the lubricating property becomes lower in a temperature range to which the temperature is raised by the thermal head at a time of continuously carrying out the transfer in low to medium density, than the other temperature ranges.
In the case of using the ink ribbon applied with this lubricant on the back face, when the transfer in low to medium density is carried out continuously, there is a high possibility for the lubricant to be peeled off due to the lowered lubricating property on the thermal head, and the peeled off lubricant to be attached and deposited on a surface of the thermal head, more specifically the heating resistors of the thermal head.
When the lubricant is attached and deposited on a surface of the heating resistors of the thermal head, it becomes harder for the heat energy to be transmitted to the ink layer, so that a partial transfer density lowering (uneven density) occurs in the formed image.
The image formation apparatus is loaded with various ink ribbons including the ink ribbon applied with such a lubricant that has a potential danger of the lowering of the lubricating property.
For this reason, it is desired for the image formation apparatus to be able to form images in good quality over a long term on image formation target objects, by devising a measure to make it harder for the lubricant of the ink ribbon to be attached and deposited on the heating resistors of the thermal head.
Also, in the image formation apparatus, when a trouble such as a card transportation error occurs in a course of transfer to one frame in the intermediate transfer film, the operation of the image formation apparatus or the printing apparatus as a whole is made to stop as an error processing. At this point, the thermal head is positioned in a middle of the frame, and the frame during the transfer remains in a state of being transferred up to a middle.
From this state, when the power is turned OFF once and then the power is turned ON again after a recovery operation, there are cases where the frame that is already transferred up to a middle on which the thermal head is positioned is erroneously recognized as a completely unused frame, and the printing is restarted by cueing that frame again to result in an improper printing.
Also, there are cases where the intermediate transfer film in which frames up to a middle among a plurality of frames are set as already used will be taken out from the apparatus once, for the purpose of the maintenance of the image formation apparatus and the like.
In that case, the intermediate transfer film will be taken out along with the detachable winding reel and supply reel.
Then, after the maintenance, at a time of installing the intermediate transfer film again along with the winding reel and the supply reel, the operation for searching a position of an unused frame in the intermediate transfer film has been carried out by the visual observation, while bridging over and feeding the intermediate transfer film from the winding reel to the supply reel.
For this reason, the maintenance efficiency is lowered, and there are concerns for causing a trouble such as unused frames are left behind or the transfer is carried out again from the already used frame, because of the failure in the cueing.
From these, there is a demand for the image formation apparatus that is capable of carrying out the cueing of an unused frame in the image formation target object in which frames up to a middle of the plurality of frames are set as already used and remaining frames are set as unused, in good quality and efficiency.